Re: [PATCH v3 net-next] l2tp: Refactor the codes with existing macros instead of literal number

On Mon, Aug 22, 2016 at 08:13:48AM +0800, Feng Gao wrote:

inline

On Mon, Aug 22, 2016 at 6:36 AM, Philp Prindeville
[off-list ref] wrote:

quoted

Inline


On 08/20/2016 09:52 AM, fgao@48lvckh6395k16k5.yundunddos.com wrote:

quoted

From: Gao Feng <redacted>

Use PPP_ALLSTATIONS, PPP_UI, and SEND_SHUTDOWN instead of 0xff,
0x03, and 2 separately.

Signed-off-by: Gao Feng <redacted>
---
  v3: Modify the subject;
  v2: Only replace the literal number with macros according to Guillaume's
advice
  v1: Inital patch

  net/l2tp/l2tp_ppp.c | 8 ++++----
  1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index d9560aa..65e2fd6 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c

@@ -177,7 +177,7 @@ static int pppol2tp_recv_payload_hook(struct sk_buff

*skb)
        if (!pskb_may_pull(skb, 2))
                return 1;
  -     if ((skb->data[0] == 0xff) && (skb->data[1] == 0x03))
+       if ((skb->data[0] == PPP_ALLSTATIONS) && (skb->data[1] == PPP_UI))

This should have used PPP_ADDRESS() and PPP_CONTROL() here.

In my initial patch, I replace them with PPP_ADDRESS() and PPP_CONTROL.
But Guillaume thought it was not clear as before.
So I revert it.

quoted

quoted

                skb_pull(skb, 2);

This magic number should go away.

Same as above.

quoted

quoted

        return 0;

@@ -282,7 +282,7 @@ static void pppol2tp_session_sock_put(struct

l2tp_session *session)
  static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
                            size_t total_len)
  {
-       static const unsigned char ppph[2] = { 0xff, 0x03 };
+       static const unsigned char ppph[2] = {PPP_ALLSTATIONS, PPP_UI};

PPP has a 4-byte header.  Where's the protocol value?

In the original code, I fail to find the code which is used to fill
the protocol value.
So I keep the two bytes header. And I thought the protocol value may be filled
by the upper layer.

And you were right. This was a macro replacement patch anyway, so you
didn't have to bring functional changes with it.
And if the protocol field was really missing, the L2TP module would
have never worked.